SPECIFIC AIMS: The purpose of the proposed research is to systematically examine the role of perceived depth on the formation of contours. The role of the depth dimension in the perception of form is often disregarded, yet there exists theoretical reason and some empirical evidence to suggest that depth is an important parameter. Recent technical developments in the generation of dynamic random element stereograms have made it possible to systematically control the depth of contours without indroducing confounding changes in the retinal stimulus. Capitalizing upon these advantages afforded by dynamic random element stereo-grams, it was shown that depth separation was a significant factor governing the extent of metacontrast masking, a visual phenomena believed to mirror the processes of contour formation (Lehmkuhle & Fox, 1978). However, the effect of perceived depth in these experiments was surprising, at least in the context of existing theory and data, in that the stimulus which was closer to the observer had a greater impact on the perception of form than the stimulus which was distal. This asymmetrical effect of depth separation on contour formation, given the appellation the front effect, seems to suggest that visual processing is enhanced for the stimulus which appears to lie in front of another. The experiments proposed here are designed to further examine the generality of this front effect in order to provide better understanding of this unique role of perceived depth in the formation of contours.